Steam boilers are well-known in the prior art and have been used in residential heating applications for years. Most steam boiler systems known in the prior art include a boiler connected to radiators by a pipe system. The pipe system allows steam to rise into the radiators, pushing the ambient air out of the radiators, until a steam vent valve on the radiator closes due to the temperature rise. The steam then condenses against the inside surface of the radiator and trickles back to the boiler by gravity through the same pipe system. Thus, most steam heating systems are open systems that are filled with air during the off cycle. The air is forced out the system when the boiler is steaming. At the end of a call for heat, the steam field collapses and draws air back into the system.
Generally, residential steam boilers are constructed of cast iron with vertical flue passages or flue ways. These vertical flue ways pass through a steam collection volume, sometimes referred to as a steam chest or steam space. The boiler is filled with water to a defined water level inside the casting. The casting acts as a heat exchange unit and a heat source is used to heat the water inside the boiler. Steam then collects above the waterline in the steam space before exiting up through the pipe system to the radiators. Occasionally, water must be added to the boiler because of intended and unintended losses. Intended losses may include loss e of water to flush or blow down the mechanical float water level control, loss e of water to flush or blow down sediment from the bottom of the boiler, and loss e of water due to the escape of steam through the vent valves. Unintended losses may include leaking radiator vents and leaking in the pipe system.
However, prior art boilers tend to corrode or degrade over time and with use. Thus, it would be beneficial to provide a boiler which is more resistant to the corrosive effect of heat and impurities in the system.